You can manage your plan directly inside the Rubik Variant Images app:

To change your plan:

1. Open the app from your Shopify admin.
2. Click Manage Plan in the sidebar.
3. Select your desired plan and confirm.

To cancel your subscription:

• Simply uninstall the app from Shopify > Settings > Apps.
  Your billing will automatically stop at the end of the current billing cycle.

There are no cancellation fees, and changes take effect immediately.